A. This procedure includes guidance on reroofing
a slate
shingle roof.

B. See also Procedure 07315-02-S for general information
concerning slate. See 07315-04-S
for supplemental
guidelines in repairing and replacing
slate roofs.

C. Safety Precautions:

1. Wear rubber-soled shoes that
have non-slip tread
(preferably sneakers
with a high top for good ankle
support). Avoid
wearing loose clothing.

2. Wear a safety belt or harness
and secure it to a
substantial chimney or
other substantial object
secured to the building.
Leave only enough slack
to work comfortably in
one area. Move and adjust
as required to work on
other sections of the roof.

3. As the work proceeds, keep
roof clear of debris and
water. Avoid stepping
on damaged or crumbling
roofing materials.

4. On slopes where the roof is
steeper than 4 inches
rise per foot, special
consideration must be given
to footing and handling
of materials. Chicken
ladders or cleats should
be used on the roof as
required for adequate
footing.

5. Do not work on shingled roofs
when wet or snow-
covered.

6. Carrying and transporting
of materials should be
limited to a safe amount
so that balance and
footing are not impaired.

C. See 01100-07-S for general project guidelines
to be
reviewed along with this procedure.
These guidelines
cover the following sections:

1. Safety Precautions

2. Historic Structures Precautions

3. Submittals

4. Quality Assurance

5. Delivery, Storage and Handling

6. Project/Site Conditions

7. Sequencing and Scheduling

8. General Protection (Surface
and Surrounding)

These guidelines should be reviewed
prior to performing
this procedure and should be followed,
when applicable,
along with recommendations from the
Regional Historic
Preservation Officer (RHPO).

1. Store materials in stacks
with provisions for air
circulation within stacks.
Protect bottom of
stacks against contact
with damp surfaces. Protect
materials against weather.

2. When the slates are stored
in an open yard, cover
the piles with overlapping
boards or use tar paper
weighted down. Adequate
protection prevents the
slates from being frozen
together. While slates
are of ample strength
when used in their proper
place, reasonable care
should be used in the
handling of the material.

3. Slates up to and including
20" X 11" may be safely
piled up to 6 tiers high.
Slates of a larger size
should never be piled
more than 4 tiers high.
Closely piled, 100 commercial
slates average 20" to
24".

1.03 PROJECT/SITE CONDITIONS

A. Environmental Requirements:

1. Do not apply new or repaired
shingle roofs in wet
weather.

2. Do not remove roofing from
structures when rain is
forecasted or in progress.

3. If roofing is to be removed
on a clear day, remove
no more than can be replaced
or repaired in one
day.

1.04 MAINTENANCE

A. Whenever possible, make inspection from ground
or from
above if possible.

B. Inspect roof for broken or missing slates, delamination
or flaking of surfaces, slate particles
collecting in
valley flashing, staining, or other
manifestations of
slate failure.

C. Look for indications that nails are corroding
or pulling
loose. Loose and missing slates,
or metallic stains are
an indication of this.

D. Inspect the underside of the roof deck from the
attic to
detect leaks. Inspect at all flashing
points carefully
for evidence of leakage such as water
stains.

E. In addition to scheduled inspections, inspect
after each
exposure to unusually severe weather
conditions such as
strong winds, hail, or long continuous
rains.

A. Slate/substitute material: roofing units
used for
replacement should match existing slate
in thickness,
color and texture. Individual
slates should be pre-
punched for nailing. See Procedure
07315-02-S for
complete list of manufacturers of natural
slate and
substitute materials.

B. Large flat-head hard copper wire nails not less
than 7/8"
long. Length should be twice the
thickness of an
individual slate plus 1 inch.

A. Inspect the deck to determine whether it is sound.
Make
whatever repairs are necessary to the
existing roof
framing to strengthen it and to level
and true the deck.
Replace rotted, damaged, or warped sheathing
or plywood.

3.02 PREPARATION

A. Surface Preparation:

1. Carefully examine, measure,
and record existing
slate shingle patterns
at edges, hips, ridges, and
other special conditions.

2. Remove existing roofing down
to the roof deck.
Salvage original slates
for reuse where possible.

3. Use a slate ripper to remove
the nails of slates in
good condition which
can be reused. Use care in
the removal and stacking
of slates to avoid damage.

4. Be careful not to damage old
metal wall and vent
flashings that may be
used as a pattern for cutting
templates. If metal
cap flashings at the chimney
and other vertical masonry
wall intersections have
not deteriorated, bend
them up out of the way so
that they may be used
again. Carefully remove
slate shingles in these
areas to avoid damaging
reusable base flashing.

2. Lap felt over all hips and
ridges a minimum of 12",
and 2" over the
metal of any valleys and gutters.

3. Omit felt at valleys, using
instead, rosin paper to
allow for thermal movement
of the sheet metal.

B. Determine exposure of slate: subtract 3"
(standard head
lap between alternating courses) from
overall length of
slates being used. Divide this
number in half to
determine final exposure.

C. If required by slope of roof, nail cant strip
at bottom
eaves, even with edge of sheathing,
to slightly raise
first courses of slate. Thickness
of cant strip allows
second course of slate to be laid correctly.
A 1/4"
taper is usually sufficient.

D. Lay under-eave starter slate. Butt of slate
shall
project 2" beyond cant strip or
bottom edge of sheathing,
and 1" beyond the edge of the sheathing
at gable ends.
Under-eave slate is shorter than other
slates. Determine
length of under-eave slates by adding
3" to the exposure
as determined in B. above. Secure
each slate with two
nails.

1. Drive the nails into the punched
holes until heads
just clear surface of
slate. The slates should
"hang" on the
nails, not be driven in so far as to
produce a strain on the
slate.

2. Use 3d nails for standard-thickness
slates up to 18
in. long. Use 4d
nails for extra-long slates, and
6d nails on hips and
ridges.

E. Lay full first course with bottom of slate even
with
bottom of under-eave slate. Position
joints between
slates so that there is a minimum 3"
off-set between the
vertical joints of the under-eave slates
below.

F. Lay second full course of slate using the exposure
as
determined in B. above. Off-set
vertical joints a
minimum of 3" from the vertical
joints in the course
below. Continue to lay main field
of slates in this
manner.

H. Build in and place all flashing pieces furnished
by the
sheet metal contractor. Valley
design shall match
original construction. Valleys
may be open, closed, or
round. Consult with slate and/or
sheet metal
manufacturer for construction details.

I. Slates overlapping sheet metal work should have
the nails
so placed as to avoid puncturing the
sheet metal.
Exposed nails should be permissible
only in top courses
where unavoidable.

J. Fit slate neatly around any pipes, ventilators,
or other
roof penetrations.